打印池

餐饮行业，打印池是必要的部件。

实现原理：每一台打印机都有自己的任务队列和处理任务队列的线程。

unit untPrintTask;

interface

uses
System.SysUtils, System.Classes,
Datasnap.DBClient, frxclass,
System.Generics.Collections;

type
TBillContent = record // 小票内容
machineNo: string; // POS机号
skyName: string; // 收款员姓名
saleNo: string; // 小票号
saleTime: TDateTime; // 销售时间
amount: Currency; // 应收
pay: Currency; // 支付
change: Currency; // 找零
prnData: OleVariant; // 小票明细：商品名称、单价、数量、金额。。。。。。
deskNo:string; // 台号
payType: string; // 支付方式
end;

type
TPrinterInfo = record // 打印机信息
prnNo: Integer; // 印机编号
prnName: string; // 印机名称
prnType: string; // 结账、厨打
prnWidth: Integer; // 50mm76mm80mm
remark: string; // 备注
prnModel: string; // 打印模版
end;

type
TOneTimePrint = record // 一次打印
printerInfo: TPrinterInfo; // 打印机信息
billContent: TBillContent; // 小票内容
end;

type
TPrintTaskThread = class(TThread) // 打印任务线程
private
FPrintQueue: TQueue<TOneTimePrint>; // 打印队列
protected
procedure Execute; override;
public
constructor Create; overload;
destructor Destroy; override;
property PrintQueue: TQueue<TOneTimePrint> read FPrintQueue
write FPrintQueue;
end;

var
g_PrintTasks: TDictionary<string, TPrintTaskThread>; // <打印机名字, TPrintTask>

implementation

{ TPrintTask }

uses untFastReport, UntSysConst;

constructor TPrintTaskThread.Create;
begin
Create(False);
FreeOnTerminate := False;
// 创建打印队列
FPrintQueue := TQueue<TOneTimePrint>.Create;
end;

destructor TPrintTaskThread.Destroy;
begin
// 释放打印队列
FreeAndNil(FPrintQueue);
inherited;
end;

procedure TPrintTaskThread.Execute;
var
OneTimePrint: TOneTimePrint;
dm: TdmFastReport;
c: TfrxComponent;
begin
while not Self.Terminated do
begin
if Assigned(FPrintQueue) and (FPrintQueue.Count > 0) then
begin
// 从任务队列中提取一个任务
OneTimePrint := FPrintQueue.Dequeue;
dm := TdmFastReport.Create(nil);
try
try
// 小票明细数据
dm.cds.Data := OneTimePrint.billContent.prnData;
// 小票模板
dm.report.LoadFromFile(OneTimePrint.printerInfo.prnModel);
// 哪个打印机
dm.report.PrintOptions.Printer := OneTimePrint.printerInfo.prnName;
// 变量赋值

c:=dm.report.FindObject('mmShopName');
if c<>nil then
TfrxMemoView(c).Memo.Text := UserInfo.ShopName;

c := dm.report.FindObject('mmMachineNo');
if c<>nil then
TfrxMemoView(c).Memo.Text := OneTimePrint.billContent.machineNo;

c:=dm.report.FindObject('mmSKY');
if c<>nil then
TfrxMemoView(c).Memo.Text := OneTimePrint.billContent.skyName;

c:= dm.report.FindObject('mmBillNo');
if c<>nil then
TfrxMemoView(c).Memo.Text := OneTimePrint.billContent.saleNo;

c:=dm.report.FindObject('mmSaleTime');
if c<>nil then
TfrxMemoView(c).Memo.Text := FormatDateTime('yyyy-mm-dd hh:nn',OneTimePrint.billContent.saleTime);

c:= dm.report.FindObject('mmDeskNo');
if c<>nil then
TfrxMemoView(c).Memo.Text := OneTimePrint.billContent.deskNo; // 台号

c:= dm.report.FindObject('mmPayType');
if c<>nil then
TfrxMemoView(c).Memo.Text := OneTimePrint.billContent.payType;

c:= dm.report.FindObject('mmAmount');
if c<> nil then
TfrxMemoView(c).Memo.Text := FormatCurr('0.00', OneTimePrint.billContent.amount);

c:=dm.report.FindObject('mmPay');
if c<>nil then
TfrxMemoView(c).Memo.Text := FormatCurr('0.00', OneTimePrint.billContent.pay);

c:= dm.report.FindObject('mmGiveChange');
if c<> nil then
TfrxMemoView(c).Memo.Text := FormatCurr('0.00', OneTimePrint.billContent.change);

// 开始打印
dm.report.PrepareReport();
dm.report.Print;
except
// 打印失败，重新加入任务队列
Self.FPrintQueue.Enqueue(OneTimePrint);
end;
finally
FreeAndNil(dm);
end;
end;

Sleep(1);
end;
end;

end.